The invention relates to a method of measuring the cross-section of an electric insulated conductor, in particular a medium-voltage and/or high-voltage insulated conductor, as well as to an apparatus for carrying out the method, in which method/apparatus an inner semiconductor, an insulation and an outer semiconductor are applied to a copper conductor in an extrusion device provided with appropriate dies, and the individual layers of the insulated conductor are crosslinked in an appropriate installation.
EP-A 0 400 310 discloses an apparatus for controlling the outside diameter of an insulated conductor, in which apparatus the outside diameter of the plastics strand emerging from the extruder is measured by means of a first measuring device immediately following the extruder and by a second measuring device following a cooling section and the actual diameter determined by this way of measuring is compared with the set diameter. A signal is formed from the difference values and this signal is used for controlling the speed of the extruder or for controlling the take-off rate of the plastics strand emerging from the extruder. With the known apparatus, only the outer diameter is measured and, in the event of any deviations, the extruder corrected correspondingly.
EP-A 0 387 508 discloses an apparatus for vulcanising or crosslinking an insulated conductor strand, which apparatus essentially comprises a tubular body which is designed with an inspection-glass fitting and essentially forms the heating and cooling zone.
With current requirements for such insulated conductors, but in particular in the case of medium-voltage and high-voltage insulated conductors having a plurality of plastic layers surrounding a copper conductor, it is necessary that, on the one hand, the copper conductor is arranged centrally in the insulated conductor and, on the other hand, the individual plastic layers have minimum possible difference in thickness over the circumference of the insulated conductor, i.e. that the individual layers are evenly distributed on the finished insulated conductor.